Yellow fever is an acute viral hemorrhagic illness transmitted primarily through the bite of infected mosquitoes. The virus targets multiple organ systems, most notably the liver and kidneys, leading to systemic inflammation. Symptoms can include high fever, muscle aches, and jaundice, with severe cases presenting with internal bleeding and multi-organ failure. The disease is endemic to tropical and subtropical regions where the specific mosquito vectors thrive. Mitigation relies on preventing mosquito breeding and outbreaks, and immunity is managed through prophylaxis and public health interventions aimed at reducing human-vector contact.